Both arms!

In conclusion, those of us directly involved in patient care must be ever-mindful that faulty BP measurements and failure to measure the BP in both arms can lead to erroneous diagnoses, unnecessary testing, and inappropriate therapy. We must also recognize that the responsibility for accurate BP measurements and for interarm BP determinations ultimately rests with us, the doctors in charge. The best way to meet that responsibility is to take the patients' BP ourselves, particularly at the initial examination, and in both arms, using correct techniques with validated measuring instruments. If, however, we delegate that responsibility, we must be certain that our surrogates and the equipment they use are reliable. Anything less is unacceptable.

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